How is the Cache score calculated?

Web Performance
1

Does the test check the page assets and calculate hits vs. misses to see which requests are getting to the server vs. being served by the CDN?

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2

The cache score doesn’t look at CDN hits or misses. Instead, it’s checking to see how long static resources are cached at the browser level.

First, it checks if static resources have proper response headers specifying their cache life (Cache-Control or Expires for example). If an individual resource is cached longer than a week, the score for that resource is 100. If the resource is cached less than a week, but greater than one hour, the score for that resource is 50. Otherwise, the resource’s cache score is 0.

The scores for all of those static resources gets added together, and then divided by the total number of static resources on the page to get the score you see mentioned in the grade.

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3

Thanks for that detailed explanation! Much appreciated!

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